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Authors: Jesús González-Enríquez, Francesca Gillespie, Stefania Lopatriello, Iñaki Imaz
Internal reviewers: Pseudo125 Pseudo125
Please refer to EFF 20.
The development of automated systems for the interpretation of the test has increased the advantage of FITs. Accurate interpretation of gFOBTs is not easy and requires well-run laboratories. An automated FIT is easier to interpret, and minimizes human error in test processing, thus making it a more objective laboratory test with excellent quality control. Furthermore, it measures the concentration of hemoglobin in the buffer, thus making it possible to choose the cutoff value. It is also possible to reinterpret the test in case of a technical problem {19}.
Direct comparison between quantitative and qualitative immunochemical fecal occult blood tests (FOBTs) has been studied. One cohort study reported that quantitative FITs offers advantages in terms of transparency and flexibility regarding the positivity threshold (e.g., specificity can be oriented toward available colonoscopy resources or personal risk profiles) and in terms of a higher level of standardization regarding test analysis and interpretation {25}.
These findings are also confirmed by another cohort study that reported a positivity rates of 8.1% for the qualitative and 2.5% for the quantitative FIT. The detection rate was 5.2% for the qualitative and 14.4% for the quantitative FIT. The odds ratio of a “suspicious cancer and cancer” versus a “normal” result was 2.73 (95% CI=2.22–3.35) for the quantitative compared to qualitative FIT {33}.
Another study about inter-observer variability in interpretation of 5 visually read FOBTs methods (standard guaiac-based method and four immunochemical methods) reported no cases of observer variability except for Hemoccult ITC test this was only minimal (on 1 sample 2 observers recorded a faint band at the cut off and one called the test negative){31}.
19. Faivre J, Dancourt V, Denis B, Dorval E, Piette C, Perrin P, et al. Comparison between a guaiac and three immunochemical faecal occult blood tests in screening for colorectal cancer. Eur J Cancer 2012; 48(16):2969-76.
25. Haug U, Hundt S, Brenner H. Quantitative immunochemical fecal occult blood testing for colorectal adenoma detection: evaluation in the target population of screening and comparison with qualitative tests. Am J Gastroenterol 2010; 105(3):682-90.
31. Tannous B, Lee-Lewandrowski E, Sharples C, Brugge W, Bigatello L, Thompson T, et al. Comparison of conventional guaiac to four immunochemical methods for fecal occult blood testing: implications for clinical practice in hospital and outpatient settings. Clin Chim Acta. febrero de 2009; 400(1-2):120-2.
33. Park MJ, Choi KS, Lee YK, Jun JK, Lee HY. A comparison of qualitative and quantitative fecal immunochemical tests in the Korean national colorectal cancer screening program. Scand J Gastroenterol 2012; 47(4):461-6.